This summer marks 100 years since the start of World War I. Many argue that the conflict was inevitable — but what if it wasn't?

Earlier we imagined a world in which Austria-Hungary evolved in a Central European Union, the German and Russian empires became modern nation states and German remained Europe's language of scholarship.

Now we're taking a look at how it would have affected life across the Atlantic, in the U.S.

The United States' rise to world power would have been slower, but it would have been more willing to intervene in conflicts in other parts of the world.

American identity would be slower to take shape because ethnic groups would continue to identify with their homelands, customs and languages.

Without a century of European turmoil, the U.S. wouldn't have hosted a century of European emigre artists and composers — no Arnold Schoenberg, Igor Stravinsky, Paul Hindemith, Bela Bartok or Kurt Weill, among others.

Popular music would look different as well, and we likely wouldn't have the song "God Bless America." Irving Berlin wrote it during World War I for soldiers to sing in an Army Review. George Gershwin might have stayed more of a classical composer with no reason to write his biggest pop hit, "Swanee."

The drive for equality — through woman's suffrage and the civil rights movement — would have happened much more slowly. Without war, fewer African-Americans would have left the rural South for jobs in the industrial North; fewer would have found better schools and progress on civil rights might have been slower in coming.

Major League Baseball probably would not have been ready for integration in Jackie Robinson's day in the late 1940s. The first player to break the color line might have been Curt Flood, in 1962.

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Transcript

MELISSA BLOCK, HOST:

This is ALL THINGS CONSIDERED from NPR News, I'm Melissa Block.

ROBERT SIEGEL, HOST:

And I'm Robert Siegel.

NIGEL STANDISH: And I'm Nigel Standish outside Westminster Cathedral and we're all looking forward very, very much to this year's royal wedding, Prince Harry and Princess Elizabetha of Germany. It's true, Elizabetha, daughter of Kaiser Wilhelm the Fifth's younger brother, Prince Henry of Prussia, was named after her future husband's grandmother and distant cousin, Queen Elizabeth II.

The German royals, the Hohenzollerns, and the English royals, the House of Saxe-Coburg-Gotha, are keeping this one in the family: Harry and Elizabetha, both descendents of Queen Victoria.

(SOUNDBITE OF CHEERING)

STANDISH: And yes, here they come now with the coaches in the background, the lovely gilding glinting in the summer sunlight. And...

SIEGEL: OK, in fact it didn't work out that way. One hundred years ago, Victoria's descendants, the crowned heads of Europe, abetted by their chancellors, prime ministers and generals, stumbled into a war that produced mass carnage and modern history. World War I begat World War II which begat the Cold War.

Well, this week, we are imagining the world as it might have been had the assassins in Sarajevo missed the mark and if the peace in Europe had held. For the notion of the Anglo-German royal wedding of 2014, we are indebted to Richard Ned Lebow, whose book, "Archduke Franz Ferdinand Lives," is a counterfactual history, the story of a world without world war.

RICHARD NED LEBOW: We can't rewind the tape of history. The most we can do is engage in what-if or counterfactual thought experiments. But by creating these extreme but nevertheless plausible versions, it gives us the vantage points outside of actual history to reflect back on the contingency and developments of the real historical world.

SIEGEL: Yesterday we imagined a world in which Austria-Hungary evolved into a Central European Union. The German and Russian empires evolved into modern nation states. German remained Europe's language of scholarship. OK, we didn't even go near Asia.

But on this side of the Atlantic, well, Margaret MacMillan's new book on the outset of World War I is called "The War that Ended Peace." And she figures without World War I and U.S. intervention in Europe the 20th century would still have been a sort of an American century.

MARGARET MACMILLAN: What would the United States have done if there weren't a war? I think its rise to world power would have been slower, but I think it would've gone on. But I think it would perhaps have been more willing to intervene in other parts of the world when things became difficult.

SIEGEL: More of an engaged world power by the late 1920s. In other respects, a little slower to develop.

MACMILLAN: I think that's right. I think the United States would have been more likely to engage. Certainly before the First World War, both Republicans, particularly those on the East Coast, and Democrats believed that the United States had an obligation to help other parts of the world. And I think that was true of Theodore Roosevelt. It was also true of Woodrow Wilson. And so, I think without the First World War that feeling might've been stronger within the United States.

SIEGEL: But we imagine the U.S. would have been different. Musicologist Kim Kowalke, of the Eastman School of Music, says without World War I, our identity as Americans would have been slower to take shape.

KIM KOWALKE: Most ethnic groups identified prior to World War I with their homelands and still maintained language and social customs. And after World War I, when immigration quotas came in and America for the first time was viewed as a world power, I think that's when most people in this country identified first and foremost as Americans of European descent or wherever, but no longer as Germans, Irish, French, Polish in America.

SIEGEL: Kowalke is head of the Kurt Weill Society. And he says without a century of European turmoil, we wouldn't have hosted a century of European emigre artists and composers.

(SOUNDBITE OF SONG, "MACK THE KNIFE")

UNIDENTIFIED MAN #1: (Singing) On a sidewalk, Sunday morning, lies a body once in life...

SIEGEL: And we imagine the impact would have been great on popular music, too.

(SOUNDBITE OF SONG, "GOD BLESS AMERICA")

UNIDENTIFIED WOMAN: (Singing) From the mountains to the prairies...

PHIL ATTEBERRY: If World War I had not happened, I don't think we would have the song "God Bless America."

SIEGEL: This is Phil Atteberry of the University of Pittsburgh. Irving Berlin wrote the song during the war for soldiers to sing in an Army review. On second thought, Berlin put it in a trunk where it remained until he dusted it off 20 years later. Atteberry also figures that George Gershwin's career would have developed differently. He says, World War I, with its domestic migrations and military deployments, occasioned a wave of popular songs about homesickness, longing for beautiful Ohio or for being back home in Indiana. And Gershwin, who straddled the worlds of classical and popular music, hit the jackpot with one of his own.

(SOUNDBITE OF SONG, "SWANEE")

UNIDENTIFIED MAN #2: (Singing) Swanee, how I love you. How I love you, my dear old Swanee. The folks up North won't see me no more when I get to that Swanee shore.

ATTEBERRY: And it became the biggest selling song that Gershwin ever had.

SIEGEL: No World War I, no trend for songs of regional longing? Atteberry figures the lack of positive reinforcement for popular song early in his career would have made for a more classical Gershwin, a composer more like Aaron Copeland. Perhaps we'd have a Gershwin symphony. But "Love is Here to Stay" would never have come in the first place.

It's also arguable that in both Europe and America, the drive for legal and social equality would have happened a lot more slowly. Historian Christopher Davidson wrote "Sleepwalkers: How Europe went to War in 1914."

CHRISTOPHER DAVIDSON: The concession of votes for women is another interesting area. The First World War accelerated the granting of women's suffrage.

SIEGEL: And American civil rights? Well, Richard Ned Lebow reasons that without World War I, fewer African-Americans would have left the rural South for jobs in the industrial North. Fewer would have found better schools, less discrimination, and a more realistic ambition for genuine progress on civil rights. With no world wars, Lebow figures, Major League Baseball would not have been ready for integration in Jackie Robinson's day in the late 1940s.

His candidate to break the color line in 1962? Well, the player who, in real life, challenged baseball's reserve clause and championed free agency: Curt Flood.

CURT FLOOD: A contract with have a beginning and an end. But the reserve clause perpetuated this year after year, even though you only had a one-year contract until you died. As a matter of fact, if they resurrected Babe Ruth, the Yankees would still own him.

DAVIDSON: He was a man of enormous inner resources and courage, a fine analytical mind, probably more so than Jackie. And he would have been the kind of person the Branch Rickey of his day would have selected to break the color bar in baseball.

SIEGEL: If there had never been a World War I or II, if that pistol had jammed in Sarajevo, or if statesmen had been shrewd enough to keep the peace, Ernest Hemingway would have said "No Farewell to Arms" and there would have been no Western front where it was rarely all quiet. No "Over There." And later on, no Rosy the Riveter to epitomize women at work. On the other hand: no Auschwitz, no Hiroshima, no Iron Curtain.

This is, of course, an exercise in imagination, not history. The imagination may be incapable of thinking up the evils that would have been perpetrated in the absence of the evils that actually were. But given the cost of lives of the war they said was fought to end war - 16 million all told - it's hard to imagine a counterfactual history with no World War I that wouldn't have been at least a little better than the real world that we inhabit 100 years after the Great War began.

BLOCK: And we invite you to send us your thoughts on how history might have been different had the First World War never happened. Go to NPR.org and click Contact at the bottom of the page. Please put: No World War I in the subject line. We'll include some of your responses in tomorrow's program. Transcript provided by NPR, Copyright NPR.